/*
  * Atrac common functions
  * Copyright (c) 2006-2008 Maxim Poliakovski
  * Copyright (c) 2006-2008 Benjamin Larsson
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**

  * @file

  */
 
 #include <math.h>
 #include <stddef.h>
 #include <stdio.h>

 #include <string.h>

 
 #include "avcodec.h"
 #include "dsputil.h"

 #include "atrac.h"

 float ff_atrac_sf_table[64];

 static float qmf_window[48];

 
 static const float qmf_48tap_half[24] = {
    -0.00001461907, -0.00009205479,-0.000056157569,0.00030117269,
     0.0002422519,  -0.00085293897,-0.0005205574,  0.0020340169,
     0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944,
    -0.000061169922,-0.01344162,    0.0024626821,  0.021736089,
    -0.007801671,   -0.034090221,   0.01880949,    0.054326009,
    -0.043596379,   -0.099384367,   0.13207909,    0.46424159
 };
 
 /**
  * Generate common tables
  */
 

 void ff_atrac_generate_tables(void)

 {
     int i;
     float s;
 
     /* Generate scale factors */

     if (!ff_atrac_sf_table[63])

         for (i=0 ; i<64 ; i++)

             ff_atrac_sf_table[i] = pow(2.0, (i - 15) / 3.0);

 
     /* Generate the QMF window. */
     if (!qmf_window[47])
         for (i=0 ; i<24; i++) {
             s = qmf_48tap_half[i] * 2.0;
             qmf_window[i] = qmf_window[47 - i] = s;
         }
 }
 
 
 /**
  * Quadrature mirror synthesis filter.
  *
  * @param inlo      lower part of spectrum
  * @param inhi      higher part of spectrum
  * @param nIn       size of spectrum buffer
  * @param pOut      out buffer
  * @param delayBuf  delayBuf buffer
  * @param temp      temp buffer
  */
 
 

 void ff_atrac_iqmf (float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp)

 {
     int   i, j;
     float   *p1, *p3;
 
     memcpy(temp, delayBuf, 46*sizeof(float));
 
     p3 = temp + 46;
 
     /* loop1 */
     for(i=0; i<nIn; i+=2){
         p3[2*i+0] = inlo[i  ] + inhi[i  ];
         p3[2*i+1] = inlo[i  ] - inhi[i  ];
         p3[2*i+2] = inlo[i+1] + inhi[i+1];
         p3[2*i+3] = inlo[i+1] - inhi[i+1];
     }
 
     /* loop2 */
     p1 = temp;
     for (j = nIn; j != 0; j--) {
         float s1 = 0.0;
         float s2 = 0.0;
 
         for (i = 0; i < 48; i += 2) {
             s1 += p1[i] * qmf_window[i];
             s2 += p1[i+1] * qmf_window[i+1];
         }
 
         pOut[0] = s2;
         pOut[1] = s1;
 
         p1 += 2;
         pOut += 2;
     }
 
     /* Update the delay buffer. */
     memcpy(delayBuf, temp + nIn*2, 46*sizeof(float));
 }